diff mbox series

[v6,7/7] ima: add policy support for the new file open MAY_OPENEXEC flag

Message ID 20200714181638.45751-8-mic@digikod.net (mailing list archive)
State New, archived
Headers show
Series Add support for O_MAYEXEC | expand

Commit Message

Mickaël Salaün July 14, 2020, 6:16 p.m. UTC 
From: Mimi Zohar <zohar@linux.ibm.com>

The kernel has no way of differentiating between a file containing data
or code being opened by an interpreter.  The proposed O_MAYEXEC
openat2(2) flag bridges this gap by defining and enabling the
MAY_OPENEXEC flag.

This patch adds IMA policy support for the new MAY_OPENEXEC flag.

Example:
measure func=FILE_CHECK mask=^MAY_OPENEXEC
appraise func=FILE_CHECK appraise_type=imasig mask=^MAY_OPENEXEC

Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
Reviewed-by: Lakshmi Ramasubramanian <nramas@linux.microsoft.com>
Acked-by: Mickaël Salaün <mic@digikod.net>
Link: https://lore.kernel.org/r/1588167523-7866-3-git-send-email-zohar@linux.ibm.com
---
 Documentation/ABI/testing/ima_policy |  2 +-
 security/integrity/ima/ima_main.c    |  3 ++-
 security/integrity/ima/ima_policy.c  | 15 +++++++++++----
 3 files changed, 14 insertions(+), 6 deletions(-)

Comments

Kees Cook July 15, 2020, 8:40 p.m. UTC | #1 
On Tue, Jul 14, 2020 at 08:16:38PM +0200, Mickaël Salaün wrote:
> From: Mimi Zohar <zohar@linux.ibm.com>
> 
> The kernel has no way of differentiating between a file containing data
> or code being opened by an interpreter.  The proposed O_MAYEXEC
> openat2(2) flag bridges this gap by defining and enabling the
> MAY_OPENEXEC flag.
> 
> This patch adds IMA policy support for the new MAY_OPENEXEC flag.
> 
> Example:
> measure func=FILE_CHECK mask=^MAY_OPENEXEC
> appraise func=FILE_CHECK appraise_type=imasig mask=^MAY_OPENEXEC
> 
> Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
> Reviewed-by: Lakshmi Ramasubramanian <nramas@linux.microsoft.com>
> Acked-by: Mickaël Salaün <mic@digikod.net>

(Process nit: if you're sending this on behalf of another author, then
this should be Signed-off-by rather than Acked-by.)
Mickaël Salaün July 16, 2020, 2:40 p.m. UTC | #2 
On 15/07/2020 22:40, Kees Cook wrote:
> On Tue, Jul 14, 2020 at 08:16:38PM +0200, Mickaël Salaün wrote:
>> From: Mimi Zohar <zohar@linux.ibm.com>
>>
>> The kernel has no way of differentiating between a file containing data
>> or code being opened by an interpreter.  The proposed O_MAYEXEC
>> openat2(2) flag bridges this gap by defining and enabling the
>> MAY_OPENEXEC flag.
>>
>> This patch adds IMA policy support for the new MAY_OPENEXEC flag.
>>
>> Example:
>> measure func=FILE_CHECK mask=^MAY_OPENEXEC
>> appraise func=FILE_CHECK appraise_type=imasig mask=^MAY_OPENEXEC
>>
>> Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
>> Reviewed-by: Lakshmi Ramasubramanian <nramas@linux.microsoft.com>
>> Acked-by: Mickaël Salaün <mic@digikod.net>
> 
> (Process nit: if you're sending this on behalf of another author, then
> this should be Signed-off-by rather than Acked-by.)

I'm not a co-author of this patch.
Randy Dunlap July 16, 2020, 2:59 p.m. UTC | #3 
On 7/16/20 7:40 AM, Mickaël Salaün wrote:
> 
> On 15/07/2020 22:40, Kees Cook wrote:
>> On Tue, Jul 14, 2020 at 08:16:38PM +0200, Mickaël Salaün wrote:
>>> From: Mimi Zohar <zohar@linux.ibm.com>
>>>
>>> The kernel has no way of differentiating between a file containing data
>>> or code being opened by an interpreter.  The proposed O_MAYEXEC
>>> openat2(2) flag bridges this gap by defining and enabling the
>>> MAY_OPENEXEC flag.
>>>
>>> This patch adds IMA policy support for the new MAY_OPENEXEC flag.
>>>
>>> Example:
>>> measure func=FILE_CHECK mask=^MAY_OPENEXEC
>>> appraise func=FILE_CHECK appraise_type=imasig mask=^MAY_OPENEXEC
>>>
>>> Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
>>> Reviewed-by: Lakshmi Ramasubramanian <nramas@linux.microsoft.com>
>>> Acked-by: Mickaël Salaün <mic@digikod.net>
>>
>> (Process nit: if you're sending this on behalf of another author, then
>> this should be Signed-off-by rather than Acked-by.)
> 
> I'm not a co-author of this patch.
> 

from Documentation/process/submitting-patches.rst:

The Signed-off-by: tag indicates that the signer was involved in the
development of the patch, or that he/she was in the patch's delivery path.
                             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Mickaël Salaün July 16, 2020, 3:22 p.m. UTC | #4 
On 16/07/2020 16:59, Randy Dunlap wrote:
> On 7/16/20 7:40 AM, Mickaël Salaün wrote:
>>
>> On 15/07/2020 22:40, Kees Cook wrote:
>>> On Tue, Jul 14, 2020 at 08:16:38PM +0200, Mickaël Salaün wrote:
>>>> From: Mimi Zohar <zohar@linux.ibm.com>
>>>>
>>>> The kernel has no way of differentiating between a file containing data
>>>> or code being opened by an interpreter.  The proposed O_MAYEXEC
>>>> openat2(2) flag bridges this gap by defining and enabling the
>>>> MAY_OPENEXEC flag.
>>>>
>>>> This patch adds IMA policy support for the new MAY_OPENEXEC flag.
>>>>
>>>> Example:
>>>> measure func=FILE_CHECK mask=^MAY_OPENEXEC
>>>> appraise func=FILE_CHECK appraise_type=imasig mask=^MAY_OPENEXEC
>>>>
>>>> Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
>>>> Reviewed-by: Lakshmi Ramasubramanian <nramas@linux.microsoft.com>
>>>> Acked-by: Mickaël Salaün <mic@digikod.net>
>>>
>>> (Process nit: if you're sending this on behalf of another author, then
>>> this should be Signed-off-by rather than Acked-by.)
>>
>> I'm not a co-author of this patch.
>>
> 
> from Documentation/process/submitting-patches.rst:
> 
> The Signed-off-by: tag indicates that the signer was involved in the
> development of the patch, or that he/she was in the patch's delivery path.
>                              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> 

OK, I though such tag had to go along with the From/Author, the
Committer or a Co-developed-by tag, but there is also this specific
case. I'll fix that in the next series.
Kees Cook July 16, 2020, 7:12 p.m. UTC | #5 
On Thu, Jul 16, 2020 at 04:40:15PM +0200, Mickaël Salaün wrote:
> 
> On 15/07/2020 22:40, Kees Cook wrote:
> > On Tue, Jul 14, 2020 at 08:16:38PM +0200, Mickaël Salaün wrote:
> >> From: Mimi Zohar <zohar@linux.ibm.com>
> >>
> >> The kernel has no way of differentiating between a file containing data
> >> or code being opened by an interpreter.  The proposed O_MAYEXEC
> >> openat2(2) flag bridges this gap by defining and enabling the
> >> MAY_OPENEXEC flag.
> >>
> >> This patch adds IMA policy support for the new MAY_OPENEXEC flag.
> >>
> >> Example:
> >> measure func=FILE_CHECK mask=^MAY_OPENEXEC
> >> appraise func=FILE_CHECK appraise_type=imasig mask=^MAY_OPENEXEC
> >>
> >> Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
> >> Reviewed-by: Lakshmi Ramasubramanian <nramas@linux.microsoft.com>
> >> Acked-by: Mickaël Salaün <mic@digikod.net>
> > 
> > (Process nit: if you're sending this on behalf of another author, then
> > this should be Signed-off-by rather than Acked-by.)
> 
> I'm not a co-author of this patch.

Correct, but you are part of the delivery path to its entry to the
tree. If you were co-author, you would include "Co-developed-by" with
a Signed-off-by. (So my nit stands)

For excruciating details:

https://www.kernel.org/doc/html/latest/process/submitting-patches.html#when-to-use-acked-by-cc-and-co-developed-by

"The Signed-off-by: tag indicates that the signer was ... in the patch’s
delivery path."

"Co-developed-by: ... is a used to give attribution to co-authors ..."
Kees Cook July 16, 2020, 7:13 p.m. UTC | #6 
On Thu, Jul 16, 2020 at 07:59:20AM -0700, Randy Dunlap wrote:
> On 7/16/20 7:40 AM, Mickaël Salaün wrote:
> > 
> > On 15/07/2020 22:40, Kees Cook wrote:
> >> On Tue, Jul 14, 2020 at 08:16:38PM +0200, Mickaël Salaün wrote:
> >>> From: Mimi Zohar <zohar@linux.ibm.com>
> >>>
> >>> The kernel has no way of differentiating between a file containing data
> >>> or code being opened by an interpreter.  The proposed O_MAYEXEC
> >>> openat2(2) flag bridges this gap by defining and enabling the
> >>> MAY_OPENEXEC flag.
> >>>
> >>> This patch adds IMA policy support for the new MAY_OPENEXEC flag.
> >>>
> >>> Example:
> >>> measure func=FILE_CHECK mask=^MAY_OPENEXEC
> >>> appraise func=FILE_CHECK appraise_type=imasig mask=^MAY_OPENEXEC
> >>>
> >>> Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
> >>> Reviewed-by: Lakshmi Ramasubramanian <nramas@linux.microsoft.com>
> >>> Acked-by: Mickaël Salaün <mic@digikod.net>
> >>
> >> (Process nit: if you're sending this on behalf of another author, then
> >> this should be Signed-off-by rather than Acked-by.)
> > 
> > I'm not a co-author of this patch.
> > 
> 
> from Documentation/process/submitting-patches.rst:
> 
> The Signed-off-by: tag indicates that the signer was involved in the
> development of the patch, or that he/she was in the patch's delivery path.
>                              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Randy beat me to it. :)
diff mbox series

Patch

diff --git a/Documentation/ABI/testing/ima_policy b/Documentation/ABI/testing/ima_policy
index cd572912c593..caca46125fe0 100644
--- a/Documentation/ABI/testing/ima_policy
+++ b/Documentation/ABI/testing/ima_policy
@@ -31,7 +31,7 @@  Description:
 				[KEXEC_KERNEL_CHECK] [KEXEC_INITRAMFS_CHECK]
 				[KEXEC_CMDLINE] [KEY_CHECK]
 			mask:= [[^]MAY_READ] [[^]MAY_WRITE] [[^]MAY_APPEND]
-			       [[^]MAY_EXEC]
+			       [[^]MAY_EXEC] [[^]MAY_OPENEXEC]
 			fsmagic:= hex value
 			fsuuid:= file system UUID (e.g 8bcbe394-4f13-4144-be8e-5aa9ea2ce2f6)
 			uid:= decimal value
diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c
index c1583d98c5e5..59fd1658a203 100644
--- a/security/integrity/ima/ima_main.c
+++ b/security/integrity/ima/ima_main.c
@@ -490,7 +490,8 @@  int ima_file_check(struct file *file, int mask)
 
 	security_task_getsecid(current, &secid);
 	return process_measurement(file, current_cred(), secid, NULL, 0,
-				   mask & (MAY_READ | MAY_WRITE | MAY_EXEC |
+				   mask & (MAY_READ | MAY_WRITE |
+					   MAY_EXEC | MAY_OPENEXEC |
 					   MAY_APPEND), FILE_CHECK);
 }
 EXPORT_SYMBOL_GPL(ima_file_check);
diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c
index e493063a3c34..6487f0b2afdd 100644
--- a/security/integrity/ima/ima_policy.c
+++ b/security/integrity/ima/ima_policy.c
@@ -406,7 +406,8 @@  static bool ima_match_keyring(struct ima_rule_entry *rule,
  * @cred: a pointer to a credentials structure for user validation
  * @secid: the secid of the task to be validated
  * @func: LIM hook identifier
- * @mask: requested action (MAY_READ | MAY_WRITE | MAY_APPEND | MAY_EXEC)
+ * @mask: requested action (MAY_READ | MAY_WRITE | MAY_APPEND | MAY_EXEC |
+ *			    MAY_OPENEXEC)
  * @keyring: keyring name to check in policy for KEY_CHECK func
  *
  * Returns true on rule match, false on failure.
@@ -527,7 +528,8 @@  static int get_subaction(struct ima_rule_entry *rule, enum ima_hooks func)
  *        being made
  * @secid: LSM secid of the task to be validated
  * @func: IMA hook identifier
- * @mask: requested action (MAY_READ | MAY_WRITE | MAY_APPEND | MAY_EXEC)
+ * @mask: requested action (MAY_READ | MAY_WRITE | MAY_APPEND | MAY_EXEC |
+ *			    MAY_OPENEXEC)
  * @pcr: set the pcr to extend
  * @template_desc: the template that should be used for this rule
  * @keyring: the keyring name, if given, to be used to check in the policy.
@@ -1091,6 +1093,8 @@  static int ima_parse_rule(char *rule, struct ima_rule_entry *entry)
 				entry->mask = MAY_READ;
 			else if (strcmp(from, "MAY_APPEND") == 0)
 				entry->mask = MAY_APPEND;
+			else if (strcmp(from, "MAY_OPENEXEC") == 0)
+				entry->mask = MAY_OPENEXEC;
 			else
 				result = -EINVAL;
 			if (!result)
@@ -1422,14 +1426,15 @@  const char *const func_tokens[] = {
 
 #ifdef	CONFIG_IMA_READ_POLICY
 enum {
-	mask_exec = 0, mask_write, mask_read, mask_append
+	mask_exec = 0, mask_write, mask_read, mask_append, mask_openexec
 };
 
 static const char *const mask_tokens[] = {
 	"^MAY_EXEC",
 	"^MAY_WRITE",
 	"^MAY_READ",
-	"^MAY_APPEND"
+	"^MAY_APPEND",
+	"^MAY_OPENEXEC"
 };
 
 void *ima_policy_start(struct seq_file *m, loff_t *pos)
@@ -1518,6 +1523,8 @@  int ima_policy_show(struct seq_file *m, void *v)
 			seq_printf(m, pt(Opt_mask), mt(mask_read) + offset);
 		if (entry->mask & MAY_APPEND)
 			seq_printf(m, pt(Opt_mask), mt(mask_append) + offset);
+		if (entry->mask & MAY_OPENEXEC)
+			seq_printf(m, pt(Opt_mask), mt(mask_openexec) + offset);
 		seq_puts(m, " ");
 	}